David Leonhardt of the NYTIMES has a rather interesting article on religious affiliation, educational attainments and income levels in the US:
http://economix.blogs.nytimes.com/2011/05/13/faith-education-and-income/?pagemode=print
http://www.nytimes.com/2011/05/15/magazine/is-your-religion-your-financial-destiny.html
A neat graphic:
http://www.nytimes.com/imagepages/2011/05/15/magazine/15-Leonhardt.html